Are you still having this issue Pedro? I have a 96 Cobra that I have replaced the pump multiple times on. Same issue: Everything is fine except WOT after around 3k+. Fuel pressure would slowly drop off when I used a gauge, nothing quick (
) and I replaced my pump beacuse of it. I used a weaker pump since it's all I had in the meanwhile and it worked great until a day or two later that WOTs were cutting up again. Replaced with a 255 Walboro and.. same thing again. Worked great, days later, issue came back. I am about to lose my mind.